Optical system driving device, lens barrel, and optical device

ABSTRACT

An optical system driving device includes a movable body that is movable in at least three degrees of freedom, and a light transmissive unit integrally mounted to the movable body. The optical system driving device also includes a driving unit that moves the movable body in at least three degrees of freedom, and a detection unit that detects a position of the movable body in each of at least three degrees of freedom. The detection unit includes a light-emitting unit that emits light toward the light transmissive unit, and an optical detector that receives light emitted from the light-emitting unit and passing through the light transmissive unit and outputs a light-receiving signal based on the received light. The detection unit also detects a position of the movable body in each of at least three degrees of freedom based on the light-receiving signal from the optical detector.

BACKGROUND

1. Technical Field

The present disclosure relates to an optical system driving device formoving a movable body which is movable in at least three degrees offreedom, and a lens barrel and an optical device which include theoptical system driving device.

2. Description of the Related Art

Patent Literature 1 discloses a technology in which alignment adjustmentincluding optical axis aligning adjustment and cat's-eye adjustment isautomatically performed by acquiring a fringe image with an imagingelement mounted to an interferometer.

CITATION LIST Patent Literature

-   PTL 1: Unexamined Japanese Patent Publication No. 2009-2673

SUMMARY

The present disclosure provides an optical system driving device, a lensbarrel, and an optical device which enable detection of a position of amovable body, which is movable in at least three degrees of freedom, ineach degree of freedom to enable high-precise position adjustment.

An optical system driving device according to the present disclosureincludes a movable body that is movable in at least three degrees offreedom, and a light transmissive unit integrally mounted to the movablebody and moving with the movable body. The optical system driving devicealso includes a driving unit that moves the movable body in each of atleast three degrees of freedom, and a detection unit that detects aposition of the movable body in each of at least three degrees offreedom. The detection unit includes a light-emitting unit that emitslight toward the light transmissive unit, and an optical detector thatreceives light emitted from the light-emitting unit and passing throughthe light transmissive unit and outputs a light-receiving signal basedon the received light. The detection unit also detects a position of themovable body in each of at least three degrees of freedom based on thelight-receiving signal from the optical detector.

The optical system driving device according to the present disclosure iseffective to detect a position of a movable body, which is movable in atleast three degrees of freedom, in each degree of freedom to enablehigh-precise position adjustment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram schematically illustrating a schematicconfiguration of a digital camera shown as an example of an opticaldevice according to the first exemplary embodiment;

FIG. 2 is a perspective view illustrating an optical system drivingdevice according to the first exemplary embodiment;

FIG. 3 is a front view illustrating the optical system driving deviceaccording to the first exemplary embodiment;

FIG. 4 is a side view illustrating the optical system driving deviceaccording to the first exemplary embodiment;

FIG. 5 is a back view illustrating the optical system driving deviceaccording to the first exemplary embodiment;

FIG. 6 is a side view illustrating a schematic configuration of a magnetunit, a first coil, and second coils in the optical system drivingdevice according to the first exemplary embodiment;

FIG. 7 is a perspective view illustrating a light transmissive unitprovided to each piece part of the optical system driving deviceaccording to the first exemplary embodiment;

FIG. 8 is a perspective view illustrating a fourth piece part of theoptical system driving device and a restriction unit according to thefirst exemplary embodiment;

FIG. 9 is a front view illustrating a fourth piece part of the opticalsystem driving device and a restriction unit according to the firstexemplary embodiment;

FIG. 10 is a front view schematically illustrating an arrangementexample of optical detectors in the optical system driving deviceaccording to the first exemplary embodiment;

FIG. 11A is an explanatory view illustrating how a spot of light passingthrough a first light transmissive unit in the optical system drivingdevice according to the first exemplary embodiment is changed on alight-receiving surface of an optical detector with the movement of thefirst light transmissive unit toward a negative side in a Z axisdirection;

FIG. 11B is an explanatory view illustrating how a spot of light passingthrough a first light transmissive unit in the optical system drivingdevice according to the first exemplary embodiment is changed on alight-receiving surface of an optical detector with the movement of thefirst light transmissive unit to a reference position in the Z axisdirection;

FIG. 11C is an explanatory view illustrating how a spot of light passingthrough a first light transmissive unit in the optical system drivingdevice according to the first exemplary embodiment is changed on alight-receiving surface of an optical detector with the movement of thefirst light transmissive unit toward a positive side in the Z axisdirection;

FIG. 12 is a flowchart illustrating a flow of a photographing processexecuted by a controller in a digital camera according to the firstexemplary embodiment;

FIG. 13 is a flowchart illustrating a flow of an attitude controlprocess executed by a lens controller in the optical system drivingdevice according to the first exemplary embodiment;

FIG. 14 is a perspective view illustrating an optical system drivingdevice according to a second exemplary embodiment;

FIG. 15A is a perspective view illustrating a light transmissive unitprovided to each piece part of the optical system driving deviceaccording to the second exemplary embodiment;

FIG. 15B is a front view schematically illustrating an arrangementexample of optical detectors in the optical system driving deviceaccording to the second exemplary embodiment;

FIG. 16 is a perspective view illustrating an optical system drivingdevice according to a third exemplary embodiment;

FIG. 17 is a sectional view of a lens holder as viewed from cut line17-17 in FIG. 16;

FIG. 18 is a front view schematically illustrating an arrangementexample of optical detectors in the optical system driving deviceaccording to the third exemplary embodiment;

FIG. 19 is a graph illustrating a difference between a light-receivingsignal from a third optical detector and a light-receiving signal from afourth optical detector according to an attitude of the lens holder inthe optical system driving device according to the third exemplaryembodiment;

FIG. 20 is a perspective view illustrating an optical system drivingdevice according to a fourth exemplary embodiment;

FIG. 21A is an explanatory view illustrating how a spot of light passingthrough a light transmissive unit is changed on a light-receivingsurface of an optical detector, when a lens holder in the optical systemdriving device according to the fourth exemplary embodiment does notmove from a reference position;

FIG. 21B is an explanatory view illustrating how a spot of light passingthrough a light transmissive unit is changed on a light-receivingsurface of an optical detector, when a lens holder in the optical systemdriving device according to the fourth exemplary embodiment moves towarda positive side in an X axis direction;

FIG. 21C is an explanatory view illustrating how a spot of light passingthrough a light transmissive unit is changed on a light-receivingsurface of an optical detector, when a lens holder in the optical systemdriving device according to the fourth exemplary embodiment moves towarda positive side in a Y axis direction;

FIG. 21D is an explanatory view illustrating how a spot of light passingthrough a light transmissive unit is changed on a light-receivingsurface of an optical detector, when a lens holder in the optical systemdriving device according to the fourth exemplary embodiment moves towarda positive side in a Z axis direction;

FIG. 21E is an explanatory view illustrating how a spot of light passingthrough a light transmissive unit is changed on a light-receivingsurface of an optical detector, when a lens holder in the optical systemdriving device according to the fourth exemplary embodiment moves towarda negative side in the Z axis direction;

FIG. 21F is an explanatory view illustrating how a spot of light passingthrough a light transmissive unit is changed on a light-receivingsurface of an optical detector, when a lens holder in the optical systemdriving device according to the fourth exemplary embodiment rotatesabout an X axis; and

FIG. 21G is an explanatory view illustrating how a spot of light passingthrough a light transmissive unit is changed on a light-receivingsurface of an optical detector, when a lens holder in the optical systemdriving device according to the fourth exemplary embodiment rotatesabout a Y axis.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments will be described in detail withreference to the accompanying drawings as necessary. It is noted,however, that descriptions in more detail than necessary will sometimesbe omitted. For example, detailed descriptions of well-known items andduplicate descriptions of substantially the same configuration willsometimes be omitted. This is to avoid unnecessary redundancy in thefollowing description and to facilitate understanding by those skilledin the art.

Note that the accompanying drawings and the following descriptions areprovided so as to facilitate fully understanding of the presentdisclosure by those skilled in the art, and these are not intended tolimit the subject matter defined by the claims.

First Exemplary Embodiment

A first exemplary embodiment will be described below with reference toFIGS. 1 to 13.

[1-1. Configuration]

[1-1-1. Optical Device]

FIG. 1 is an explanatory diagram schematically illustrating a schematicconfiguration of a digital camera shown as one example of an opticaldevice according to the first exemplary embodiment. As illustrated inFIG. 1, digital camera 1 includes camera body 2 and lens barrel 3.

In the present exemplary embodiment, a three-dimensional orthogonalcoordinate system is set as illustrated in FIG. 1. A Z axis directionmatches optical axis 5 of later-described optical system 4. A positiveside in the Z axis direction means a subject side in the optical axisdirection, and the opposite side is specified as a negative side. An Xaxis direction matches a width direction of digital camera 1 in a planeorthogonal to optical axis 5. A Y axis direction matches a heightdirection of digital camera 1 in a plane orthogonal to optical axis 5.

Lens barrel 3 includes optical system 4, zoom driving unit 31, focusdriving unit 32, zoom encoder 33, focus encoder 34, and optical systemdriving device 100.

Optical system 4 includes first lens group 41, second lens group 42, andthird lens group 43.

First lens group 41 moves along optical axis 5 so as to vary a zoommagnification. Second lens group 42 corrects aberration of opticalsystem 4 through a control of an attitude of second lens group 42relative to optical axis 5. Third lens group 43 adjusts a focus state ofa subject image along optical axis 5.

Zoom driving unit 31 is, for example, a stepping motor that moves firstlens group 41 along optical axis 5.

Focus driving unit 32 is, for example, a stepping motor that moves thirdlens group 43 along optical axis 5.

Zoom encoder 33 detects a zoom position (variable magnificationposition) of first lens group 41, and outputs the detected position tocontroller 22 (described later) of camera body 2.

Focus encoder 34 detects a focus position of third lens group 43, andoutputs the resultant to controller 22 of camera body 2.

Optical system driving device 100 controls an attitude of second lensgroup 42 relative to optical axis 5. Optical system driving device 100includes support mechanism 110 (see FIG. 2), aberration correctiondriving unit 120, light-emitting units 131, optical detectors 132, andlens controller 36.

Aberration correction driving unit 120 moves second lens group 42relative to optical axis 5.

Light-emitting unit 131 and optical detector 132 detect a position ofsecond lens group 42.

Lens controller 36 is a control device controlling a core of lens barrel3. Lens controller 36 is connected to units mounted to lens barrel 3,and performs various sequence controls of lens barrel 3. Lens controller36 includes a CPU (Central Processing Unit) including a control circuit,a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.Lens controller 36 can implement various functions when a program storedin the ROM is read into the CPU.

Support mechanism 110 supports second lens group 42 so as to be movable.

The detail of optical system driving device 100 will be described later.

Camera body 2 includes imaging element 21 and controller 22.

Imaging element 21 is, for example, a CCD (Charge Coupled Device) whichconverts an optical image formed with optical system 4 of lens barrel 3into an electrical signal. Imaging element 21 is driven with a timingsignal. Notably, imaging element 21 may be a CMOS (Complementary MetalOxide Semiconductor) sensor.

Controller 22 is a control device controlling a core of camera body 2.Controller 22 controls units of digital camera 1 based on operationsignals from operation units such as a shutter button or a zoom lever.Specifically, controller 22 includes a CPU, a ROM, a RAM, and the like.Controller 22 can implement various functions when a program stored inthe ROM is read into the CPU. For example, when a zoom position is inputfrom zoom encoder 33, and a focus position is input from focus encoder34, controller 22 calculates a position correction value of second lensgroup 42 based on the zoom position and the focus position, and outputsthe position correction value to lens controller 36. Lens controller 36controls aberration correction driving unit 120 based on the positioncorrection value and a light-receiving signal output from opticaldetector 132, thereby controlling an attitude of second lens group 42.

[1-1-2. Optical System Driving Device]

Next, optical system driving device 100 will be described.

FIG. 2 is a perspective view illustrating optical system driving device100 according to the first exemplary embodiment. FIG. 3 is a front viewillustrating optical system driving device 100 according to the firstexemplary embodiment. FIG. 4 is a side view illustrating optical systemdriving device 100 according to the first exemplary embodiment. FIG. 5is a back view illustrating optical system driving device 100 accordingto the first exemplary embodiment.

As illustrated in FIGS. 2 to 5, optical system driving device 100includes support mechanism 110, aberration correction driving unit 120,light-emitting units 131, and optical detectors 132.

Support mechanism 110 includes lens holder 140, light transmissive units150, and restriction unit 160.

Lent holder 140 is one example of a movable body which is movable in atleast three degrees of freedom. A degree of freedom means a degree inwhich one system can be displaced. In the three-dimensional orthogonalcoordinate system, a total number of directions in which a system can bemoved out of six moving directions is indicated as a degree of freedom,the six moving directions being an X-axis direction, a Y-axis direction,a Z-axis direction, a rotating direction about the X axis, a rotatingdirection about the Y axis, and a rotation direction about the Z axis.For example, the case in which a system can be moved in only one movingdirection is indicated as “one degree of freedom”, and the case in whicha system can be moved in two directions is indicated as two degrees offreedom.

Lens holder 140 includes two lenses 42 a, 42 b in second lens group 42.The present exemplary embodiment describes that lens holder 140 holdstwo lenses 42 a, 42 b. However, lens holder 140 may hold only one lens,or three or more lenses.

Lens holder 140 encloses two lenses 42 a, 42 b, which are coaxiallydisposed, to hold these lenses. Lens holder 140 is provided with firstpiece part 141 and second piece part 142 at both ends in the Y axisdirection, first piece part 141 and second piece part 142 projectingoutward along the Y axis direction. Lens holder 140 is also providedwith third piece part 143 and fourth piece part 144 at both ends in theX axis direction, third piece part 143 and fourth piece part 144projecting outward along the X axis direction. Each of first piece part141, second piece part 142, and third piece part 143 is provided withlight transmissive unit 150.

Each of frames 145, 146, 147, 148 having generally rectangular shape ina plan view is provided between each of piece parts 141, 142, 143, 144around lens holder 140. Each of frames 145, 146, 147, 148 holds magnetunit 170. First coil 181 for moving lens holder 140 in the X axisdirection and Y axis direction is mounted to each magnet unit 170 at thepositive side in the Z axis direction. A pair of second coils 182 formoving lens holder 140 in the Z axis direction is mounted to each magnetunit 170 at the negative side in the Z axis direction.

FIG. 6 is a side view illustrating a schematic configuration of magnetunit 170, first coil 181, and second coils 182 in optical system drivingdevice 100 according to the first exemplary embodiment.

As illustrated in FIG. 6, magnet unit 170 includes two plate magnets171, 172 which have a rectangular shape in a plan view and are equal insize. A pair of main surfaces of plate magnets 171, 172 is exposed fromframes 145, 146, 147, 148, the main surfaces being opposite to eachother in the Z axis direction. Each of the pair of main surfaces isparallel to planes of lenses 42 a, 42 b orthogonal to the optical axis.Plate magnets 171, 172 are magnetized such that different magnet polesare formed in the thickness direction. Plate magnets 171, 172 aredisposed to be adjacent to each other with different magnet polesdirecting upward (to the positive side in the Z axis direction). In thepresent exemplary embodiment, magnet unit 170 includes two plate magnets171, 172. However, a magnet unit including one magnetized plate magnetmay be used.

First coil 181 is disposed so as to face the main surfaces of the platemagnets 171, 172 at the positive side in the Z axis direction. Firstcoil 181 is wound into substantially an ellipse as a whole, and thelonger axis direction of the ellipse extends along the longitudinaldirection of plate magnets 171, 172. First coil 181 is disposed to spantwo plate magnets 171, 172. A pair of opposing longitudinal parts offirst coil 181 is disposed to face the substantially central part ofeach of plate magnets 171, 172 in the width direction. With this,magnetic field M1 perpendicular to the main surfaces of plate magnets171, 172 at the positive side in the Z axis direction interlinks thelongitudinal parts of first coil 181. Electric current generated with apower supply to first coil 181 interlinks magnetic field M1, so thatthrust force (thrust force in the direction parallel to X-Y plane) inX-Y plane is generated. Specifically, with the control of electriccurrent to first coil 181 in magnet unit 170, magnet unit 170 can bemoved in X-Y plane (in the direction parallel to X-Y plane).

On the other hand, a pair of second coils 182 is disposed so as to facethe main surfaces of plate magnets 171, 172 at the negative side in theZ axis direction. Each of second coils 182 is wound into substantiallyan ellipse as a whole, and the longer axis direction of the ellipseextends along the longitudinal direction of plate magnets 171, 172. Eachof a pair of second coils 182 is disposed to face each of two platemagnets 171, 172. Longitudinal parts of a pair of second coils 182 aredisposed to face both ends of plate magnets 171, 172 in the widthdirection. With this, magnetic field M2 parallel to the main surfaces ofplate magnets 171, 172 at the negative side in the Z axis directioninterlinks the longitudinal parts of second coil 182. Electric currentgenerated with a power supply to second coils 182 interlinks magneticfield M2, so that thrust force in the Z axis direction is generated.

Specifically, with the control of electric current to a pair of secondcoils 182 in magnet unit 170, magnet unit 170 can be moved in the Z axisdirection.

When electric currents to first coil 181 and a pair of second coils 182in all magnet units 170 are comprehensively controlled, the attitude oflens holder 140 with respect to the Z axis direction can be controlled.Specifically, lens holder 140 can be moved with six degrees of freedom,that is, in the X axis direction, the Y axis direction, the Z axisdirection, the rotating direction about the X axis, the rotatingdirection about the Y axis, and the rotating direction about the Z axis.

Magnet unit 170, first coil 181, and second coils 182 form aberrationcorrection driving unit 120.

FIG. 7 is a perspective view illustrating light transmissive unit 150provided to each piece part of optical system driving device 100according to the first exemplary embodiment. FIG. 7 illustrates lighttransmissive unit 150 alone. Light transmissive unit 150 is a condensercondensing light. For example, it is a cylindrical lens. In the presentexemplary embodiment, a convex cylindrical lens is used as one example.However, a concave cylindrical lens may be used, so long as it condenseslight. Light transmissive unit (first light transmissive unit 150 a)provided to first piece part 141 has axis 151 along the Y axis directionand convex surface 152 facing the negative side in the Z axis direction.Flat surface 153 of first light transmissive unit 150 a opposite toconvex surface 152 is parallel to the planes of lenses 42 a, 42 borthogonal to the optical axis. The same configuration as describedabove is applied to light transmissive unit (second light transmissiveunit 150 b) provided to second piece part 142.

Light transmissive unit (third light transmissive unit 150 c) providedto third piece part 143 has axis 151 along the X axis direction andconvex surface 152 facing the negative side in the Z axis direction.Flat surface 153 of third light transmissive unit 150 c opposite toconvex surface 152 is parallel to the planes of lenses 42 a, 42 borthogonal to the optical axis.

As illustrated in FIGS. 2 to 5, fourth piece part 144 projects from theperipheral edge of lens holder 140 in the X axis direction. Fourth piecepart 144 is engaged with restriction unit 160 fixed to lens barrel 3.

FIG. 8 is a perspective view illustrating fourth piece part 144 ofoptical system driving device 100 and restriction unit 160 according tothe first exemplary embodiment. FIG. 9 is a front view illustratingfourth piece part 144 of optical system driving device 100 andrestriction unit 160 according to the first exemplary embodiment.

Fourth piece part 144 includes body 155, arm 156, and shaft 157.

Body 155 projects from the end of lens holder 140 along the X axisdirection. Arm 156 extends outward from the tip of body 155. Arm 156 isformed such that the width in the Y axis direction is smaller than body155. Shaft 157 is a protruding part mounted at the tip of arm 156 tohave substantially a spherical shape. The diameter of shaft 157 islarger than the width of arm 156 in the Y axis direction. The center ofarm 156 in the Y axis direction is overlapped with the center of shaft157. With this, both ends of shaft 157 in the Y axis direction projectfrom arm 156 with the same width.

Restriction unit 160 restricts one degree of freedom out of degrees offreedom in which lens holder 140 can be moved. Specifically, restrictionunit 160 restricts the movement of lens holder 140 in the rotatingdirection about the Z axis. With this, lens holder 140 is movable infive degrees of freedom.

Restriction unit 160 is fixed at a position which is near lens holder140 and opposite to fourth piece part 144. Restriction unit 160 includesbase 161 and support part 162. Base 161 erects along the Z axisdirection from a support member (not illustrated) in lens barrel 3.Support part 162 extends from the tip of base 161 toward lens holder 140along the X axis direction. Support part 162 has a storage recess 163for storing shaft 157. Storage recess 163 is recessed from the tip endface of support part 162 at the positive side in the X axis directiontoward the negative side in the X axis direction, and is also open inthe Z axis direction. A pair of planes 164, 165 defining storage recess163 is parallel to each other, and is parallel to Z-X plane, planes 164,165 being opposite to each other in the Y axis direction. In otherwords, width H of storage recess 163 in the Y axis direction is almostentirely uniform. A pair of planes 164, 165 holds shaft 157 in the Yaxis direction with a point contact. A pair of opposing planes 164, 165is separated from each other with width H in order to be in contact withshaft 157. Specifically, shaft 157 slides on a pair of planes 164, 165with a spherical surface which forms an outer surface, so that shaft 157can be translated in the X axis direction and Z axis direction within apair of planes 164, 165. When a basis of the three-dimensionalcoordinate system is set on a center of shaft 157, shaft 157 can bemoved in the rotating direction about the X axis, the rotating directionabout the Y axis, and the rotating direction about the Z axis as beingheld by a pair of planes 164, 165, since the spherical surface servingas the outer surface of shaft 157 slides on a pair of planes 164, 165.

Specifically, when a basis of the three-dimensional coordinate system isset on a center of shaft 157, shaft 157 can be moved in five degrees offreedom, that is, in the X axis direction, the Z axis direction, therotating direction about the X axis, the rotating direction about the Yaxis, and the rotating direction about the Z axis.

The degree of freedom in which shaft 157 is movable has been describedabove. However, a degree of freedom is different, when it is consideredfrom lenses 42 a, 42 b held by lens holder 140. The movement of shaft157 in the Y axis direction is restricted by restriction unit 160.Therefore, when the basis of the three-dimensional coordinate system isset on the center of lens 42 a, lens holder 140 is unable to rotateabout the optical axis (Z axis). When lens holder 140 is rotated aboutthe Z axis based on shaft 157 and shaft 157 is moved in the X axisdirection, even if the movement of shaft 157 in the Y axis direction isrestricted, lens holder 140 can be moved in the Y axis direction.

As described above, when the basis of the three-dimensional coordinatesystem is set on a center of lens 42 a, lens holder 140 can be moved infive degrees of freedom, that is, in the X axis direction, the Y axisdirection, the Z axis direction, the rotating direction about the Xaxis, and the rotating direction about the Y axis.

Although not illustrated, a regulation piece for preventingdisengagement of shaft 157 from storage recess 163 is provided in lensbarrel 3 for preventing shaft 157 from being disengaged from storagerecess 163.

Shaft 157 is not necessarily sphere as a whole. Shaft 157 may have aspherical surface only within a range with which at least a pair ofplanes 164, 165 can be in contact.

Light-emitting unit 131 emits light toward light transmissive unit 150,and it is a laser diode emitting laser light, for example. Asillustrated in FIGS. 2 to 4, three light-emitting units 131 areprovided. Each of light-emitting units 131 is disposed so as to emitlight toward light transmissive unit 150 at the positive side of lighttransmissive unit 150 in the Z axis direction. An LED (Light EmittingDiode) can be used as light-emitting unit 131.

Optical detector 132 receives light, which is emitted fromlight-emitting unit 131 and passes through light transmissive unit 150,and outputs a light-receiving signal based on the received light.Optical detector 132 is a quadrant photodetector, for example. Itconverts a quantity of light received in each separation region into avoltage, and outputs the voltage to the outside as a light-receivingsignal. A light-receiving signal has a larger value, as an areareceiving light is larger. Three optical detectors 132 are provided soas to make a pair with each of light-emitting units 131. Each of opticaldetectors 132 is disposed to face light-emitting unit 131 through lighttransmissive unit 150. A spot of light emitted from light-emitting unit131 and passing through light transmissive unit 150 is formed on alight-receiving surface of each of optical detectors 132.

Light-emitting unit 131 and optical detector 132 are fixed to thesupport member (not illustrated) in lens barrel 3, and the relativepositional relation of light-emitting unit 131 and optical detector 132does not vary. On the other hand, the positional relation between lighttransmissive unit 150 and both of light-emitting unit 131 and opticaldetector 132 varies.

FIG. 10 is a front view schematically illustrating an arrangementexample of optical detectors 132 in optical system driving device 100according to the first exemplary embodiment.

Each of optical detectors 132 has separation boundaries L1 and L2.Separation boundaries L1 and L2 are set to bisect each other at thecenter of the light-receiving surface, thereby equally separating thelight-receiving surface into four.

As illustrated in FIG. 10, optical detector 132 is disposed such thatseparation boundary L1 and separation boundary L2 are shifted at 45degrees relative to the X axis and the Y axis respectively.

FIG. 11A is an explanatory view illustrating how a spot of light passingthrough first light transmissive unit 150 a (see FIG. 7) in opticalsystem driving device 100 according to the first exemplary embodiment ischanged on the light-receiving surface of optical detector 132 with themovement of first light transmissive unit 150 a in the Z axis direction.FIG. 11B is an explanatory view illustrating how a spot of light passingthrough first light transmissive unit 150 a is changed on thelight-receiving surface of optical detector 132 with the movement offirst light transmissive unit 150 a to a reference position in the Zaxis direction. FIG. 11C is an explanatory view illustrating how a spotof light passing through first light transmissive unit 150 a is changedon the light-receiving surface of optical detector 132 with the movementof first light transmissive unit 150 a to the positive side in the Zaxis direction.

As illustrated in FIG. 11B, when first light transmissive unit 150 a islocated on the reference position in the Z axis direction, light passingthrough first light transmissive unit 150 a forms substantially circularspot P on the light-receiving surface. Since first light transmissiveunit 150 a is a cylindrical lens having axis 151 along the Y axisdirection, a focal position in the X axis direction and a focal positionin the Y axis direction are shifted from each other to causeastigmatism. Therefore, the shape of spot P varies depending on thedistance of the optical axis (Z axis direction). Specifically, whenfirst light transmissive unit 150 a moves toward the negative side inthe Z axis direction, that is, when first light transmissive unit 150 amoves close to optical detector 132, the shape of spot P becomes anellipse illustrated in FIG. 11A. On the other hand, when first lighttransmissive unit 150 a moves toward the positive side in the Z axisdirection, that is, when first light transmissive unit 150 a moves awayfrom optical detector 132, the shape of spot P becomes an ellipseillustrated in FIG. 11C. The longitudinal direction of the ellipse ofspot P is shifted by 90 degrees depending on whether first lighttransmissive unit 150 a moves toward the positive side or toward thenegative side in the Z axis direction from the reference position.

Even if first light transmissive unit 150 a illustrated in FIG. 7 movesin the Y axis direction or rotates about the X axis, the position andshape of spot P are not changed, since axis 151 of first lighttransmissive unit 150 a extends along the Y axis direction. When firstlight transmissive unit 150 a moves in the X axis direction or rotatesabout the Y axis, the position of spot P moves in the X axis direction.This is similarly applied to a spot formed with light passing throughsecond light transmissive unit 150 b and formed on the light-receivingsurface of second optical detector 132 b.

Even if third light transmissive unit 150 c illustrated in FIG. 7 movesin the X axis direction or rotates about the Y axis, the position andshape of spot P are not changed, since axis 151 of third lighttransmissive unit 150 c extends along the X axis direction. When thirdlight transmissive unit 150 c moves in the Y axis direction or rotatesabout the X axis, the position of spot P moves in the Y axis direction.

From these, relations represented by equations (1) to (6) describedbelow are established.

Specifically, as illustrated in FIG. 10, a1, b1, c1, d1 are each alight-receiving signal (voltage value) of each of separation regions offirst optical detector 132 a facing first light transmissive unit 150 a(see FIG. 7). a2, b2, c2, d2 are each a light-receiving signal (voltagevalue) of each of separation regions of second optical detector 132 bfacing second light transmissive unit 150 b (see FIG. 7). a3, b3, c3, d3are each a light-receiving signal (voltage value) of each of separationregions of third optical detector 132 c facing third light transmissiveunit 150 c (see FIG. 7).

In the description below, x is a variable indicating X-coordinate at thecenters of lenses 42 a, 42 b. y is a variable indicating Y-coordinate atthe centers of lenses 42 a, 42 b. z is a variable indicatingZ-coordinate at the centers of lenses 42 a, 42 b. θx is a variableindicating an angle about the X axis at the centers of lenses 42 a, 42b. θy is a variable indicating an angle about the Y axis at the centersof lenses 42 a, 42 b. In addition, α1, α2, α3, β11, β12, β21, β22, γ1,γ2 are correction coefficients. Suitable values are obtained forcorrection coefficients from various experiments and simulations.

PD11=a1−d1=α1×x+β21×θy  (1)

PD12=a1+d1−(b1+c1)=α3×z+β12×θx  (2)

PD21=a2−d2=α1×x+β21×θy  (3)

PD22=a2+d2−(b2+c2)=α3×z−β12×θx  (4)

PD31=c3−b3=α2×y+β11×θx  (5)

PD32=a3+d3−(b3+c3)=α3×z+β22×θy  (6)

The relations represented by equations (7) to (11) can be derived bysolving these equations (1) to (6).

θx=γ1×(PD12−PD22)  (7)

θy=γ2×(PD32−(PD12+PD22/2))  (8)

x=PD11−β2×θy=(PD11−β21×γ2×(PD32−(PD12+PD22/2)))/α1  (9)

y=PD31−β1×θx=(PD31−β11×γ1×(PD12−PD22))/α2  (10)

z=(PD12+PD22)/(2×α3)  (11)

Lens controller 36 performs calculation based on a light-receivingsignal output from each of optical detectors 132 and the above relationequations (1) to (11) to detect a position of lens holder 140 in eachdegree of freedom. Lens controller 36 is a calculation unit calculatinga position in each degree of freedom. Detection unit 200 includeslight-emitting units 131, optical detectors 132, and lens controller 36(see FIG. 1).

[1-2. Operation]

An operation of digital camera 1 thus configured will be describedbelow.

FIG. 12 is a flowchart illustrating a flow of a photographing processexecuted by controller 22 in digital camera 1 according to the firstexemplary embodiment.

As illustrated in FIG. 12, when zooming operation is performed with thezoom lever, controller 22 controls zoom driving unit 31 through lenscontroller 36 to move first lens group 41 along an optical axis duringthe zooming operation (step S1). Controller 22 recognizes a zoomposition of first lens group 41 based on an output result from zoomencoder 33 upon the end of the zooming operation, and stores this zoomposition (step S2).

When an autofocus operation is performed with the shutter button,controller 22 then controls focus driving unit 32 through lenscontroller 36 to move third lens group 43 along the optical axis duringthe autofocus operation (step S3). Controller 22 recognizes a focusposition of third lens group 43 based on an output result from focusencoder 34, and stores this focus position (step S4).

Controller 22 then calculates a position correction value of second lensgroup 42 from the zoom position of first lens group 41 and the focusposition of third lens group 43 (step S5).

Controller 22 then outputs the position correction value of second lensgroup 42 to lens controller 36 to cause lens controller 36 to execute anattitude control process (step S6).

FIG. 13 is a flowchart illustrating a flow of the attitude controlprocess executed by lens controller 36 in optical system driving device100 according to the first exemplary embodiment.

As illustrated in FIG. 13, lens controller 36 controls currents of firstcoils 181 and second coils 182 in all magnet units 170 based on theposition correction value acquired from controller 22 (step S61).Specifically, lens controller 36 obtains correction values in each offive degrees of freedom from the position correction value, anddetermines current values for first coils 181 and second coils 182 inall magnet units 170 from the correction value of each degree offreedom.

With this, lens holder 140 moves in five degrees of freedom, that is, inthe X axis direction, the Y axis direction, the Z axis direction, therotating direction about the X axis, and the rotating direction aboutthe Y axis (step S62).

Then, lens controller 36 detects a position of lens holder 140 in eachdegree of freedom (step S63). Specifically, lens controller 36 allowseach light-emitting unit 131 to emit light toward each optical detector132 through each light transmissive unit 150. With this, alight-receiving signal from each separation region is output to lenscontroller 36 from each optical detector 132. Lens controller 36performs calculation based on the light-receiving signals and the aboverelation equations to detect a position of lens holder 140 in eachdegree of freedom.

Then, lens controller 36 determines whether or not the detected positionof lens holder 140 in each degree of freedom matches the position ineach degree of freedom based on the position correction value (S64).

When they are determined to match each other in step S64 (Yes in stepS64), lens controller 36 ends the attitude control process, and proceedsto step S7 illustrated in FIG. 12.

When they are determined not to match each other in step S64 (No in stepS64), lens controller 36 calculates a new position correction value fromthe detected position of lens holder 140 in each degree of freedom (stepS65), and proceeds to step S61.

As illustrated in FIG. 12, in step S7, controller 22 executes imaging,when the shutter button is fully depressed.

[1-3. Effects]

As described above, according to the present exemplary embodiment, lighttransmissive units 150 are integrally provided to lens holder 140 thatis a movable body movable in at least three degrees of freedom.Therefore, light transmissive units 150 move with lens holder 140. Withthis configuration, light transmissive units 150 move with the samedegree of freedom as lens holder 140. When light transmissive units 150move with lens holder 140, at least one of the shape, intensity, anddistribution of spot P which is formed on optical detector 132 withlight passing through light transmissive units 150 is changed inresponse to the movement of light transmissive units 150. Opticaldetectors 132 output light-receiving signals based on received light.Accordingly, with use of the light-receiving signals, the position oflens holder 140 in each degree of freedom can be obtained with highprecision.

As a result, the position of the movable body, which is movable in atleast three degrees of freedom, in each degree of freedom can bedetected, whereby high-precise position control is enabled.

With the configuration in which light transmissive units 150 fordetecting a position in each degree of freedom are integrally providedto lens holder 140, light transmissive units 150 can move with the samedegree of freedom as lens holder 140. Accordingly, positions in at leastthree degrees of freedom can be detected with a simple configuration.

Since light transmissive units 150 are condensers, light passing throughlight transmissive units 150 can be condensed and emitted to opticaldetectors 132. The intensity of light is increased on optical detectors132 with light condensing, so that light variation can reliably bedetected.

The spot of light is decreased with light condensing, whereby compactoptical detectors 132 can be used.

Since the condensers are cylindrical lenses, precise position detectionusing an astigmatic method is enabled.

In addition, three sets of light-emitting unit 131 and optical detector132 are provided. Therefore, when light-receiving signals of threeoptical detectors 132 are used in combination, positions of lens holder140 in four or more degrees of freedom (in the present exemplaryembodiment, five degrees of freedom) can be detected.

As described above, optical system driving device 100 according to thepresent exemplary embodiment includes a movable body which is movable inat least three degrees of freedom and corresponds to lens holder 140,and light transmissive unit 150 which is integrally provided to themovable body and moves with the movable body. The optical system drivingdevice also includes a driving unit which moves the movable body in eachof at least three degrees of freedom and corresponds to aberrationcorrection driving unit 120, and detection unit 200 which detects aposition of the movable body in each of at least three degrees offreedom. Detection unit 200 includes light-emitting unit 131 that emitslight toward light transmissive unit 150, and optical detector 132 thatreceives light emitted from light-emitting unit 131 and passing throughlight transmissive unit 150 and outputs a light-receiving signal basedon the received light. Detector 200 also detects a position in each ofat least three degrees of freedom based on the light-receiving signal ofoptical detector 132. With this configuration, the position of themovable body, which is movable in at least three degrees of freedom, ineach degree of freedom can be detected, whereby high-precise positioncontrol is enabled.

Light transmissive unit 150 may be a condenser condensing light. Withthis configuration, optical detector 132 can reliably detect variationof light.

In addition, the condenser may be a cylindrical lens. With thisconfiguration, precise position detection using an astigmatic method isenabled.

In addition, detection unit 200 may include three or more sets oflight-emitting unit 131 and optical detector 132. With thisconfiguration, positions of the movable of body in four or more degreesof freedom can be detected.

In addition, the movable body may be movable in at least five degrees offreedom. With this configuration, positions of the movable body in fivedegrees of freedom can be detected. Accordingly, the number ofcomponents can be reduced.

In addition, detection unit 200 may detect a position of the movablebody in each of five degrees of freedom. With this configuration, thenumber of components can be reduced.

In addition, optical device 1 according to the present exemplaryembodiment may include optical system driving device 100 and opticalsystem 4 including a plurality of lenses. At least one of the pluralityof lenses may be held with the movable body. With this, high-preciseposition control of the movable body is enabled.

In addition, optical device 1 according to the present exemplaryembodiment may include optical system driving device 100 and an opticalsystem including a plurality of lenses. At least one of the plurality oflenses may be held with the movable body, and light transmissive unit150 may be the lens held with the movable body. With this, high-preciseposition control of the movable body is enabled.

Second Exemplary Embodiment 2-1. Configuration

A second exemplary embodiment will be described below with reference toFIGS. 14, 15A, and 15B. The configurations similar to the firstexemplary embodiment are identified by the same reference numerals, andthe description for similar configurations and operations may be omittedin some cases.

FIG. 14 is a perspective view illustrating optical system driving device100A according to the present exemplary embodiment.

As illustrated in FIG. 14, light transmissive unit 150 (fourth lighttransmissive unit 150 d) is mounted to fourth piece part 144A of lensholder 140A in optical system driving device 100A. As illustrated inFIG. 15A, fourth light transmissive unit 150 d is a convex cylindricallens. Axis 151 thereof extends along the X axis direction, and convexsurface 152 faces the negative side in the Z axis direction.

Elastic member 167 such as a spring is mounted on a main surface of eachof first piece part 141A, second piece part 142A, third piece part 143A,and fourth piece part 144A at the negative side in the Z axis direction.Each of elastic members 167 extends parallel to the Z axis direction.One end of each of elastic members 167 is mounted to the main surface ofeach of piece parts 141A, 142A, 143A, 144A at the negative side in the Zaxis direction, and the other end is mounted to a support member (notillustrated) in lens barrel 3. Due to these elastic members 167, themovement of lens holder 140A in any degree of freedom is not restricted,and lens holder 140A is held so as to be swingable. Specifically, lensholder 140A can be moved in six degrees of freedom, that is, in the Xaxis direction, the Y axis direction, the Z axis direction, the rotatingdirection about the X axis, the rotating direction about the Y axis, andthe rotating direction about the Z axis.

Light-emitting unit 131 and optical detector 132 are provided to beopposite to each other in the Z axis direction across fourth lighttransmissive unit 150 d.

FIG. 15B is a front view schematically illustrating an arrangementexample of optical detectors 132 in optical system driving device 100Aaccording to the second exemplary embodiment.

As illustrated in FIG. 15B, optical detector 132 is disposed such thatseparation boundary L1 and separation boundary L2 are shifted at 45degrees relative to the X axis and the Y axis respectively.

First light transmissive unit 150 a, second light transmissive unit 150b, and third light transmissive unit 150 c are arranged in the samemanner as illustrated in FIG. 10.

Even if fourth light transmissive unit 150 d moves in the X axisdirection or rotates about the Y axis, the position and shape of spot Pare not changed, since axis 151 of fourth light transmissive unit 150 dextends along the X axis direction. When fourth light transmissive unit150 d moves in the Y axis direction or rotates about the X axis, theposition of spot P moves in the Y axis direction.

From these, relations represented by equations (12) to (19) describedbelow are established.

Specifically, as illustrated in FIG. 15B, a1, b1, c1, d1 are each alight-receiving signal (voltage value) of each of separation regions offirst optical detector 132 a facing first light transmissive unit 150 a.a2, b2, c2, d2 are each a light-receiving signal of each of separationregions of second optical detector 132 b facing second lighttransmissive unit 150 b. a3, b3, c3, d3 are each a light-receivingsignal of each of separation regions of third optical detector 132 cfacing third light transmissive unit 150 c. a4, b4, c4, d4 are each alight-receiving signal of each of separation regions of fourth opticaldetector 132 d facing fourth light transmissive unit 150 d.

In the description below, x is a variable indicating X-coordinate at thecenters of lenses 42 a, 42 b. y is a variable indicating Y-coordinate atthe centers of lenses 42 a, 42 b. z is a variable indicatingZ-coordinate at the centers of lenses 42 a, 42 b. θx is a variableindicating an angle about the X axis at the centers of lenses 42 a, 42b. θy is a variable indicating an angle about the Y axis at the centersof lenses 42 a, 42 b. θz is a variable indicating an angle about the Zaxis at the centers of lenses 42 a, 42 b. In addition, α1, α2, α3, β11,β12, β21, β22, β3 are correction coefficients. Suitable values areobtained for correction coefficients from various experiments andsimulations.

PD11=a1−d1=α1×x+β21×θy+β3×θz  (12)

PD12=a1+d1−(b1+c1)=α3×z+β12×θx  (13)

PD21=a2−d2=α1×x+β21×θy−β3×θz  (14)

PD22=a2+d2−(b2+c2)=α3×z−β12×θx  (15)

PD31=c3−b3=α2×y+β11×θx+β3×θz  (16)

PD32=a3+d3−(b3+c3)=α3×z+β22×θy  (17)

PD41=c4−b4=α2×y+β12×θx−β3×θz  (18)

PD42=a4+d4−(b4+c4)=α3×z−β22×θy  (19)

The relations represented by equations (20) to (25) can be derived bysolving these equations (12) to (19).

θx=(PD12−PD22)/(2×α3)  (20)

θy=(PD32−PD42)/(2×α3)  (21)

θz=(PD11−PD21+PD31−PD41)/(4×β3)  (22)

x=((PD11+PD21)−β21×(PD32−PD42)/α3)/(2×α3)  (23)

y=((PD31+PD41)−(PD11−PD21+PD31−PD41)/2)/(2×α3)  (24)

z=(PD12+PD22+PD32+PD42)/4  (25)

Lens controller 36 performs calculation based on a light-receivingsignal output from each of optical detectors 132 and the above relationequations (12) to (25) to detect a position of lens holder 140 in eachdegree of freedom. Lens controller 36 controls currents of first coils181 and second coils 182 in all magnet units 170 based on the positioncorrection value acquired in the same manner as in the first exemplaryembodiment (FIG. 13). With this, lens holder 140A can be moved in sixdegrees of freedom, that is, in the X axis direction, the Y axisdirection, the Z axis direction, the rotating direction about the Xaxis, the rotating direction about the Y axis, and the rotatingdirection about the Z axis.

2-2. Effects

As described above, according to the present exemplary embodiment, foursets of light-emitting unit 131 and optical detector 132 are provided.Therefore, when light-receiving signals of four optical detectors 132are used in combination, positions in six degrees of freedom can bedetected. With this, high-precise position control is enabled.

Third Exemplary Embodiment 3-1. Configuration

A third exemplary embodiment will be described below with reference toFIGS. 16 to 19. The configurations similar to the first exemplaryembodiment are identified by the same reference numerals, and thedescription for similar configurations and operations may be omitted insome cases.

FIG. 16 is a perspective view illustrating optical system driving device100B according to the third exemplary embodiment.

As illustrated in FIG. 16, lens holder 140B in optical system drivingdevice 100B does not include first piece part 141 to third piece part143, and includes only fourth piece part 144 having shaft 157. Themovement of shaft 157 in the Y axis direction is restricted byrestriction unit 160. With this, lens holder 140B can be moved in fivedegrees of freedom, that is, in the X axis direction, Y axis direction,Z axis direction, rotating direction about the X axis, and the rotatingdirection about the Y axis, as in the first exemplary embodiment.

FIG. 17 is a sectional view of lens holder 140B as viewed from a cutline 17-17 in FIG. 16. Specifically, cut line 17-17 is a line parallelto the X axis and passing through the centers of lenses 42 a, 42 b.

As illustrated in FIG. 17, light-emitting unit 131B is provided outwardof lens 42 a at the positive side in the X axis direction.Light-emitting unit 131B emits light along the X axis direction towardthe end of lens 42 a at the positive side in the X axis direction. Apart of light emitted from light-emitting unit 131B is reflected on thesurface at the end of lens 42 a at the positive side in the X axisdirection. Optical detector 132B is disposed on an optical path of lightreflected on the surface of lens 42 a.

A part of light emitted from light-emitting unit 131B also enters lens42 a, is totally reflected on a boundary surface of lens 42 a severaltimes (three times in the present exemplary embodiment), and then,emitted to the outside of lens 42 a from the surface at the end of lens42 a at the negative side in the X axis direction. Optical detector 132Bis disposed on an optical path of light emitted from lens 42 a.

As described above, light emitted from light-emitting unit 131B passes(is reflected or transmitted) through lens 42 a to reach opticaldetector 132B. In other words, lens 42 a functions as a lighttransmissive unit.

Similarly, one light-emitting unit 131B and a pair of optical detectors132B are provided in the Y axis direction. Light-emitting unit 131Bprovided in the Y axis direction is disposed outward of lens 42 a at thepositive side in the Y axis direction. A pair of optical detectors 132Bis disposed on an optical path of light emitted from light-emitting unit131B. In the Y axis direction either, light emitted from light-emittingunit 131B passes (is reflected or transmitted) through lens 42 a toreach optical detector 132B.

FIG. 18 is a front view schematically illustrating an arrangementexample of optical detectors 132 in optical system driving device 100Baccording to the third exemplary embodiment.

As illustrated in FIG. 18, optical detector 132B is disposed such thatseparation boundary L1 extends along the Y axis, and separation boundaryL2 extends along the X axis.

In FIG. 18, a1, b1, c1, d1 are each a light-receiving signal of each ofseparation regions of optical detector (first optical detector 132Ba)disposed at the positive side in the Y axis direction. a2, b2, c2, d2are each a light-receiving signal of each of separation regions ofoptical detector (second optical detector 132Bb) disposed at thenegative side in the Y axis direction. a3, b3, c3, d3 are each alight-receiving signal of each of separation regions of optical detector(third optical detector 132Bc) disposed at the positive side in the Xaxis direction. a4, b4, c4, d4 are each a light-receiving signal of eachof separation regions of optical detector (fourth optical detector132Bd) disposed at the negative side in the X axis direction.

FIG. 19 is a graph illustrating a difference between a light-receivingsignal from third optical detector 132Bc and a light-receiving signalfrom fourth optical detector 132Bd based on an attitude of lens holder140B in optical system driving device 100B according to the thirdexemplary embodiment.

As illustrated in FIG. 19, when lens holder 140B is displaced toward thepositive side in the Z axis direction, the light-receiving signal fromthird optical detector 132Bc becomes a large positive value, while thelight-receiving signal from fourth optical detector 132Bd becomes nearlyzero. When lens holder 140B is displaced toward the negative side in theZ axis direction, the light-receiving signal from third optical detector132Bc becomes a large negative value, while the light-receiving signalfrom fourth optical detector 132Bd becomes nearly zero.

When lens holder 140B is displaced toward the positive side about the Xaxis, the light-receiving signal from third optical detector 132Bcbecomes a small positive value, while the light-receiving signal fromfourth optical detector 132Bd becomes a small negative value. When lensholder 140B is displaced toward the negative side about the X axis, thelight-receiving signal from third optical detector 132Bc becomes a smallnegative value, while the light-receiving signal from fourth opticaldetector 132Bd becomes a small positive value.

When lens holder 140B is displaced toward the positive side in the Yaxis direction, the light-receiving signal from third optical detector132Bc becomes nearly zero, while the light-receiving signal from fourthoptical detector 132Bd becomes a large negative value. When lens holder140B is displaced toward the negative side in the Y axis direction, thelight-receiving signal from third optical detector 132Bc becomes nearlyzero, while the light-receiving signal from fourth optical detector132Bd becomes a large positive value. As described above, light-emittingunit 131 and optical detector 132B are disposed such that sensitivitiesof light-receiving signals to optical detectors 132B relative to thedisplacement in the Z axis direction, displacement in the Y axisdirection, and the rotation about the X axis differ.

Similarly, a difference between a light-receiving signal from firstoptical detector 132Ba and a light-receiving signal from second opticaldetector 132Bb is also obtained. From these, relations represented byequations (26) to (39) described below are established.

In the description below, x is a variable indicating X-coordinate at thecenters of lenses 42 a, 42 b. y is a variable indicating Y-coordinate atthe centers of lenses 42 a, 42 b. z is a variable indicatingZ-coordinate at the centers of lenses 42 a, 42 b. θx is a variableindicating an angle about the X axis at the centers of lenses 42 a, 42b. θy is a variable indicating an angle about the Y axis at the centersof lenses 42 a, 42 b. In addition, α1, α2, α3, β1, β2 are correctioncoefficients. Suitable values are obtained for correction coefficientsfrom various experiments and simulations.

PD11=(a1+b1)−(c1+d1)=α3×z  (26)

PD12=(a1+c1)−(b1+d1)=α1×x+β1×θx  (27)

PD21=(a2+b2)−(c2+d2)=α2×y  (28)

PD22=(a2+c2)−(b2+d2)=α1×x+β1×θx  (29)

PD31=(a3+c3)−(b3+d3)=α3×z  (30)

PD32=(a3+b3)−(c3+d3)=α2×y+β2×θy  (31)

PD41=(a4+c4)−(b4+d4)=α1×x  (32)

PD42=(a4+b4)−(c4+d4)=α2×y+β2×θy  (33)

PD12=PD22  (34)

PD32=PD42  (35)

PD11−PD21=α3×z−α2×y  (36)

PD12−PD31=α1×x−α3×z  (37)

PD31−PD41=α3×z−α1×x  (38)

The relations represented by equations (39) to (43) can be derived bysolving these equations (26) to (38).

x=α1×PD31  (39)

y=α2×PD21  (40)

z=α3×(PD11+PD31)/2  (41)

θx=(PD12−α1×PD31)/β1  (42)

θy=(PD32−α2×PD21)/β2  (43)

Lens controller 36 performs calculation based on a light-receivingsignal output from each of optical detectors 132 and the above relationequations (26) to (44) to detect a position of lens holder 140 in eachdegree of freedom. Lens controller 36 controls currents of first coils181 and second coils 182 in all magnet units 170 based on the positioncorrection value acquired in the same manner as in the first exemplaryembodiment (FIG. 13). With this, lens holder 140A moves in five degreesof freedom, that is, in the X axis direction, the Y axis direction, theZ axis direction, the rotating direction about the X axis, and therotating direction about the Y axis.

3-2. Effects

As described above, the present exemplary embodiment brings thefollowing effect in addition to the effects of the first and secondexemplary embodiments. Specifically, lens 42 a held by lens holder 140Bserves as a light transmissive unit. Therefore, a position of lensholder 140B movable in each degree of freedom can be detected withoutseparately providing a light transmissive unit exclusively used forposition detection. Accordingly, the number of components can bereduced.

In addition, two optical detectors 132B are provided corresponding toone light-emitting unit 131B. Therefore, less number of light-emittingunits 131B can be used than the embodiment in which light-emitting unit131B and optical detector 132B are provided in one-to-onecorrespondence, whereby the number of components can be reduced.

Fourth Exemplary Embodiment 4-1. Configuration

A fourth exemplary embodiment will be described below with reference toFIGS. 20 and 21A to 21G.

FIG. 20 is a perspective view illustrating optical system driving device100C according to the fourth exemplary embodiment. The configurationssimilar to the first exemplary embodiment are identified by the samereference numerals, and the description for similar configurations andoperations may be omitted in some cases. As illustrated in FIG. 20, lensholder 140C in optical system driving device 100C does not include firstpiece part 141 and second piece part 142, and includes only third piecepart 143 and fourth piece part 144 having shaft 157. The movement ofshaft 157 in the Y axis direction is restricted by restriction unit 160.With this, lens holder 140C can be moved in five degrees of freedom,that is, in the X axis direction, Y axis direction, Z axis direction,rotating direction about the X axis, and the rotating direction aboutthe Y axis, as in the first exemplary embodiment.

Light transmissive unit 150C with a substantially disc-like shape, suchas a condenser lens, is mounted to third piece part 143. Light-emittingunit 131 is disposed so as to emit light toward light transmissive unit150C at the positive side of light transmissive unit 150C in the Z axisdirection. Optical detector 132C is provided at the position facinglight-emitting unit 131 across light transmissive unit 150C. Opticaldetector 132C is an imaging element such as a CCD. The imaging elementimages spot P, converts light into voltage on pixel basis, and outputsthe voltage as a light-receiving signal. The imaging element has morelight-receiving surfaces (pixels) than a quadrant photodetector.Therefore, the imaging element can detect the shape, intensity, anddistribution of spot P with higher precision.

When lens holder 140C moves, spot P of light emitted from light-emittingunit 131 and passing through light transmissive unit 150C is changed onthe light-receiving surface of optical detector 132C in response to anamount of variation and moving direction of lens holder 140C.

FIG. 21A is an explanatory view illustrating how spot P of light passingthrough light transmissive unit 150C is changed on the light-receivingsurface of optical detector 132C, when lens holder 140C in opticalsystem driving device 100C according to the fourth exemplary embodimentdoes not move from a reference position. In FIGS. 21A to 21G, ahorizontal direction is specified as an X axis direction, and a verticaldirection is specified as an Y axis direction. FIG. 21B is anexplanatory view illustrating how spot P of light passing through lighttransmissive unit 150C is changed on the light-receiving surface ofoptical detector 132C, when lens holder 140C in optical system drivingdevice 100C according to the fourth exemplary embodiment moves towardthe positive side in the X axis direction. FIG. 21C is an explanatoryview illustrating how spot P of light passing through light transmissiveunit 150C is changed on the light-receiving surface of optical detector132C, when lens holder 140C moves toward the positive side in the Y axisdirection. FIG. 21D is an explanatory view illustrating how spot P oflight passing through light transmissive unit 150C is changed on thelight-receiving surface of optical detector 132C, when lens holder 140Cmoves toward the positive side in the Z axis direction. FIG. 21E is anexplanatory view illustrating how spot P of light passing through lighttransmissive unit 150C is changed on the light-receiving surface ofoptical detector 132C, when lens holder 140C moves toward the negativeside in the Z axis direction. FIG. 21F is an explanatory viewillustrating how spot P of light passing through light transmissive unit150C is changed on the light-receiving surface of optical detector 132C,when lens holder 140C rotates about the X axis. FIG. 21G is anexplanatory view illustrating how spot P of light passing through lighttransmissive unit 150C is changed on the light-receiving surface ofoptical detector 132C, when lens holder 140C rotates about the Y axis.

In FIG. 21A, the center of spot P matches the center of optical detector132C. In FIG. 21B, when lens holder 140C moves in the X axis direction,spot P also moves in the X axis direction in response to the movingamount of lens holder 140C. In FIG. 21C, when lens holder 140C moves inthe Y axis direction, spot P also moves in the Y axis direction inresponse to the moving amount of lens holder 140C. In FIG. 21D, whenlens holder 140C moves toward the positive side in the Z axis direction,spot P increases, and the intensity thereof is decreased as a whole inresponse to the moving amount of lens holder 140C. In FIG. 21E, whenlens holder 140C moves toward the negative side in the Z axis direction,spot P decreases, and the intensity thereof is increased as a whole inresponse to the moving amount of lens holder 140C. In FIG. 21F, whenlens holder 140C rotates about the X axis, spot P spreads at thepositive side or negative side in the Y axis direction in response tothe rotation amount of lens holder 140C. In FIG. 21G, when lens holder140C rotates about the Y axis, spot P spreads at the positive side ornegative side in the X axis direction in response to the rotation amountof lens holder 140C.

With comprehensive analysis of these relations, a position of lensholder 140C in each degree of freedom can be detected fromlight-receiving signals of many pixels acquired by imaging spot P withoptical detector 132C.

4-2. Effects

As described above, the present exemplary embodiment brings thefollowing effect in addition to the effects of the first and secondexemplary embodiments. Specifically, since optical detector 132C is animaging element, the shape, intensity, and distribution of spot P can bedetected with higher precision. Accordingly, even if only one opticaldetector 132C is used, a position of lens holder 140C in each degree offreedom can be detected. When only one optical detector 132C is used, itis only necessary to use one light-emitting unit 131, whereby the numberof components can further be reduced.

Other Exemplary Embodiments

As presented above, the first to fourth exemplary embodiments have beendescribed as an example of the technology described in the presentapplication. However, the technology in the present disclosure is notlimited to these, and can be applied to embodiments in which variouschanges, replacements, additions, omissions, or the like are made.Moreover, each constituent element described in the first to fourthexemplary embodiments described above can be combined to provide a newembodiment.

Other exemplary embodiments will be described below.

The first to fourth exemplary embodiments describe that optical systemdriving device 100 moves a lens as an example. However, other opticalelements can be moved with optical system driving device 100. Examplesof optical elements other than lens include a mirror and a light guideplate.

The first to fourth exemplary embodiments indicate an imaging devicesuch as digital camera 1 as an example of an optical device. However,other optical devices may be used. A projection device such as aprojector may be used as other optical devices.

The first to fourth exemplary embodiments indicate aberration correctiondriving unit 120 including magnet unit 170, first coil 181, and secondcoil 182 as an example of a driving unit. A unit that can move lensholder 140 (movable body) in each degree of freedom in which lens holder140 is movable may be used as the driving unit. For example, a multipledegree of freedom actuator using a motor may be used as the drivingunit.

The first to fourth exemplary embodiments indicate that lens holder 140which is a movable body is movable in five degrees of freedom or sixdegrees of freedom. However, it is only necessary that lens holder 140is movable in at least three degrees of freedom.

The fourth exemplary embodiment indicates a CCD as an imaging elementthat is one example of an optical detector. An imaging element imagingspot P, converting light into voltage on pixel basis, and outputting thevoltage as a light-receiving signal may be used. Accordingly, theimaging element is not limited to a CCD. However, if a CCD is used asthe imaging element, the imaging element is available with low cost. ACMOS image sensor may also be used as the imaging element. Use of a CMOSimage sensor as the imaging element is effective to suppress powerconsumption.

The first to fourth exemplary embodiments indicate lens controller 36 asan example of a calculation unit. The calculation unit may be physicallyconfigured in any way, so long as it can detect a position in eachdegree of freedom from a light-receiving signal from optical detector132. A programmable microcomputer may be used as the calculation unit.With this, processing content can be changed by changing a program,whereby a degree of freedom of designing the calculation unit can beenhanced. The calculation unit may also be implemented with hard logic.The calculation unit implemented by hard logic is effective to increaseprocessing speed. The calculation unit may include only one element, ormay physically include a plurality of elements. When the calculationunit is configured to include a plurality of elements, each controldescribed in claims may be implemented by another element. In this case,it can be considered that the plurality of elements form one calculationunit. In addition, the calculation unit and a member having anotherfunction may include one element.

As presented above, the exemplary embodiments have been described as anexample of the technology described in the present disclosure. For thispurpose, the accompanying drawings and the detailed description areprovided.

Therefore, components in the accompanying drawings and the detaildescription may include not only components essential for solvingproblems, but also components that are provided to illustrate the abovedescribed technology and are not essential for solving problems.Therefore, such inessential components should not be readily construedas being essential based on the fact that such inessential componentsare shown in the accompanying drawings or mentioned in the detaileddescription.

Further, the above described embodiments have been described toexemplify the technology according to the present disclosure, andtherefore, various modifications, replacements, additions, and omissionsmay be made within the scope of the claims and the scope of theequivalents thereof.

The present disclosure is applicable to an optical system driving devicefor moving a movable body which is movable in at least three degrees offreedom, and an optical device including the optical system drivingdevice. Specifically, the present disclosure is applicable to a digitalcamera, a movie, a projector, and the like.

What is claimed is:
 1. An optical system driving device comprising: amovable body that is movable in at least three degrees of freedom; alight transmissive unit that is integrally mounted to the movable bodyand moves with the movable body; a driving unit configured to move themovable body in each of the at least three degrees of freedom; and adetection unit that detects a position of the movable body in each ofthe at least three degrees of freedom, wherein the detection unitincludes: a light-emitting unit that emits light toward the lighttransmissive unit; and an optical detector that receives light emittedfrom the light-emitting unit and passing through the light transmissiveunit and outputs a light-receiving signal based on the received light,the detection unit detecting a position of the movable body in each ofthe at least three degrees of freedom based on the light-receivingsignal from the optical detector.
 2. The optical system driving deviceaccording to claim 1, wherein the light transmissive unit is a condenserthat condenses light.
 3. The optical system driving device according toclaim 2, wherein the condenser is a cylindrical lens.
 4. The opticalsystem driving device according to claim 1, wherein the detection unitincludes three or more sets of the light-emitting unit and the opticaldetector.
 5. The optical system driving device according to claim 1,wherein the optical detector is an imaging element.
 6. The opticalsystem driving device according to claim 1, wherein the movable body ismovable in at least five degrees of freedom.
 7. The optical systemdriving device according to claim 1, wherein the detection unit detectsa position of the movable body in each of five degrees of freedom. 8.The optical system driving device according to claim 1, wherein themovable body has a configuration capable of supporting an opticalelement, and the at least three degrees of freedom include a degree inwhich the movable body is capable of being displaced along a first axisthat is an optical axis; a degree in which the movable body is capableof being displaced in a plane orthogonal to the first axis and along asecond axis that is orthogonal to the first axis; and a degree in whichthe movable body is capable of being displaced along a third axisorthogonal to the second axis in the plane.
 9. The optical systemdriving device according to claim 8, wherein the at least three degreesof freedom further include a degree in which the movable body is capableof being displaced about the second axis, and a degree in which themovable body is capable of being displaced about the third axis.
 10. Theoptical system driving device according to claim 9, wherein the at leastthree degrees of freedom further include a degree in which the movablebody is capable of being displaced about the first axis.
 11. The opticalsystem driving device according to claim 8, wherein the lighttransmissive unit is disposed above at least one of the second axis andthe third axis.
 12. A lens barrel comprising: the optical system drivingdevice according to claim 1; and an optical system including one or moreoptical elements, wherein at least one of the one or more opticalelements is held with the movable body.
 13. A lens barrel comprising:the optical system driving device according to claim 1; and an opticalsystem including one or more optical elements, wherein at least one ofthe one or more optical elements is held with the movable body, and thelight transmissive unit is the optical element held with the movablebody.
 14. An optical device comprising: the lens barrel according toclaim 12; and a body that acquires or projects an image through theoptical system in the lens barrel.
 15. An optical device comprising: thelens barrel according to claim 13; and a body that acquires or projectsan image through the optical system in the lens barrel.